LiHV and LiPo batteries have different battery chemistry. If you were to charge a normal LiPo up to 4.35v per cell it would likely explode or at least puff up. The different battery chemistry in LiHV batteries allows the batteries to have a higher capacity to weight ratio. (For example, a 1500mah LiPo would be noticeably heavier than a 1500mah LiHV) A LiHV battery can hold more power and performance in a battery that weighs less.
This ability to pack more power into the battery does come at a cost though as it does reduce the longevity of the battery significantly. Any good quality standard Lipo should hold up to 300+ charge cycles (If taken care of properly) whereas a LiHV battery may begin to swell up at only 30-40 cycles.
LiHV batteries are very useful when it comes to serious racing though. The high performance and increased power per weight ratio give racers an advantage when racing, they will just need to replace batteries a lot more often.
It just depends on whether you want a little bit longer flight at the expense of needing to replace your batteries a lot more often.
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